Internet Services: Infrastructure for Charging and Billing

Transcription

1 Internet Services: Infrastructure for Charging and Billing John Cushnie 1) David Hutchison 2) Huw Oliver 3) 1) Distributed Multimedia Research Group, Lancaster University, UK 2) Distributed Multimedia Research Group, Lancaster University, UK 3) Internet Research Institute, HP Labs, Bristol, UK Abstract: The Internet is evolving into a ubiquitous platform for the delivery of services and content. This evolution brings with it a sea of change, as it rapidly becomes the chosen medium for commercial published material and communication. The evolution of Internet services, both mobile and fixed, presents the industry and academia with many research and engineering challenges. Among these the challenge of charging and billing for Internet services stands out. Also where the charging and billing should belong both commercially and physically within the public and private networks is an important area for research. This paper discusses where charging is currently implemented in the Internet, and the requirements for the necessary infrastructure to charge for Internet services and applications, now and into the future. The focus of this research is on the technical challenges of generation, collection and processing of the charging and billing data within the network. To support this research an experimental charging platform is presented that is currently under development. Keywords: billing, charging, accounting, Internet, QoS 1. Introduction The introduction of new Internet services and applications and the commercial interest in the Internet economy brings the challenge of charging and billing for the provided services, applications and content. The Internet has changed the way that business is carried out on a global scale. This makes it an enabler that allows companies to be more efficient by providing instant communication with customers and suppliers. Individuals also benefit from this communication provision, and the services and applications available today and into the future. Metering may be defined as the counting of the network data at the lowest level; Accounting may then be performed using the metering data collected from the network to attribute resource usage on a user basis; Charging and Billing may then be implemented using the accounting data produced. Charging and billing for the Internet, including mobile Internet, have been identified as important research areas by many organisations over the past years, leading to many excellent publications, conferences and workshops [4, 5, 16, 17, 21, 24]. The world is going on-line with the Internet, and the associated business opportunities with such a revolution are enormous. The global provision of information and services is a great motivator for industry and academia alike. To make the most of this opportunity efficient methods for charging and billing need to be proposed, developed and deployed. A question still to be resolved is where does charging and billing in the Internet belong? With telephony networks the question is easy to answer and rests with the network carrier that the consumer is tied to as a main provider. With the Internet the question becomes more complicated as the number of services and applications available increase, together with as many providers that may supply them. The physical points and methods for charging in the Internet have also not yet been defined on a standard basis. Some Internet providers impose charges based on capacity or bandwidth. Some charge according to duration. Some charge on a subscription basis, and some don t charge at all and rely on advertisement and other revenue streams. In order to research charging models and their impact on the Internet market we have implemented an experimental charging platform. This is adaptable to Internet networks using mobile, wireless or fixed access infrastructure, and is not tied to commercial products. The charging platform is described in terms of the architecture and research objectives and observations made so far. 2. To charge or not to charge The overhead associated with charging for Internet access and services can be large. This depends on the charging methods and policies implemented. So the question has to be asked whether the overhead is worthwhile from a financial and business viewpoint. This includes cost of deployment of the required systems

2 and infrastructure to enable charging for Internet usage. With the increasing commercialisation of the Internet an expectation to pay for services is normal. How much should be charged for specific services is an important question for the service providers. The service providers can use charging data to model marketing scenarios that result in feedback for their customer charges. The introduction of Internet services to mobile telephony networks brings a convergence of voice and data billing. This will inevitably lead to more complexity in the charging and billing infrastructure. Where to charge in the network Internet usage can be charged for on many levels. Charging may be implemented on access to Internet services based on capacity, duration and Quality of Service (QoS). Charging may also be made for specific content communicated, on a volume/capacity, value or subscription basis. Charging may be implemented indirectly by using credit/debit transactions whilst online or offline to provide access to the services and applications. The billing data may be generated on the Internet servers that provide the services, applications and content to the end user. Internet charging may also be implemented between the service providers on the Internet. This covers the interchange of data and services, with agreed Service Level Agreements (SLAs) in place. The communication routes between the source and sink on the Internet often span several networks. This incurs charges and cross-charges with several service and content providers. If the charging can be kept local to the provider the collection and audit of the charges becomes less complex. Motivations for charging Two motivations for charging and billing in the Internet are (i) recovery of financial investment for the provision of the infrastructure and (ii) to act as congestion control through differentiating service levels according to price. The financial investment involved with provision of Internet networks and services range in magnitude. From very small one-man outfits to the multinational corporations, such as Time-Warner-AOL, they all have a presence on the Internet. In order for commercial organisations to use the Internet they must perceive value. The revenue that can be generated usually is a measure of this perceived value. Congestion control is also a motivation for charging for Internet access. This may be used to discourage excess resource usage by price. It has been demonstrated [20], and is widely accepted, that the Internet is currently congested only at the access network level with the core networks are relatively under-utilised. By ensuring that the access and core networks are over-provisioned then the current best-effort services of the Internet may become almost guaranteed or assured services. In this case the motivation for Quality of Service (QoS) engineering in the network is reduced. This is a controversial viewpoint not supported by the large amount of QoS based research being carried out. The over-provisioned network with average utilisation may be a way forward, but with the rapid continual growth of the Internet this is a constantly moving target, with constantly changing metrics. A combination of QoS enabled networks and over-provisioning is how the Internet is being evolved at present. Unmetered Charging In Europe consumers have had to pay for Internet access since the introduction of these services. This is usually on a metered basis via their Internet Service Providers (ISPs) and telephony companies. Market forces and the intervention of the national telecommunications regulatory bodies have slowly reduced the price charged for the telephony access. Unmetered access services are now beginning to appear to match those that are standard in the US and elsewhere. Over and above the required authentication and admission control no additional charging and billing system or infrastructure is required with unmetered charging. This results in financial advantage for both the consumer and providers. Free Internet service providers Charging and payment have been embraced by the new Internet economy. Initially highly subsidised by industry and government, Internet access is now increasingly expensive. In the early days of the commercial Internet many Internet Service Provider companies were created, which generated enormous wealth from subscription based services. Freeserve [10], the UK ISP, revolutionised the Internet Service industry with the introduction of a subscription free service. This model was based on using a 70%/30% kickback on the call charges made to access the service via the local-call telephone service operated by British Telecom [3]. This also gave the service provider further advantage as the revenue for the service was collected by British Telecom. This reduced the risk of lost income from subscribers who refuse to pay the call charges. Also the cost associated with implementing a charging system for Internet usage was removed. Many UK and international ISPs have followed the example set by Freeserve and this is now one of the preferred business models used by subscription based ISPs in Europe. Another approach used successfully by many Internet content providers is the advertisement only funding model. Here the revenue from advertising is used to fund the service. This model borrows from old economy publishing,

3 where free newspapers are run on an adverts-only basis, removing the need and overhead associated with a customer charging system and infrastructure. Government Provided Internet There are on-going debates about whether Internet access should be provided by governments, like the road networks and other social infrastructure. This provision may then be subject to government-based taxes and charges, similar to the TV license scheme, for example. This then allows the Internet and content service providers to generate service and content related revenue streams in isolation to the cost of the Internet connection and access infrastructure. Services and applications may then be charged for according to their perceived value in the market place. Internet services present and future The number of services on the Internet is increasing day by day. Services include directories, on-line grocery delivery, streaming audio and video content, multicast content delivery, on-line gaming and others. These services all present challenging business models, some of which require direct support from the Internet delivery model. This support includes metering information and/or protocol support for the collection of billing and payment information. is currently accepted as the most used application on the Internet. A new killer application for the future Internet has yet to emerge, or it is possible that will retain the title. To aid charging, accounting protocols need to be included with future services on the Internet, for both charging and also monitoring purposes of the network traffic. Such protocols and architectures may include Diameter [7] as currently being proposed by the IETF [13] and IRTF [14]. 3. What to charge for? If Internet services and applications are charged for then the service providers need to decide on what basis the charges will be made. The required infrastructure, methods and procedures can then be deployed to meet these requirements. Charging Requirements The technical requirements for being able to charge for Internet services and the associated Internet access are understood and widely documented. Charging may take place on a duration or volume basis or it may be related to the actual value of the service or content being consumed. For example, is considered to be a basic Internet service, with low elastic bandwidth requirements and as such should be low cost. Whereas live video streams of international sporting events have more perceived value and higher bandwidth requirements, and as such may demand a higher perceived value. If the sporting event is a minority sport, for example archery, then the perceived value differs accordingly. The business models behind the charging and billing decisions made by the service and content providers are interesting but best left to economists and management scientists to discuss. Most current Internet charging mechanisms are based on packet counting or extensions to communication protocols to collect and transport the required charging information. Other approaches include the use of micro-payments [19] associated with network transactions and communication. A layered approach to allow metering, accounting, charging, pricing and billing information to be captured and processed from the network may be used. Such architectures have been proposed and documented in past research such as SUSIE [25] and the ETSI NA8 GONOW working group [9]. Packet Counting and Duration charging In order to implement packet counting or duration based charging schemes for Internet services, extra network infrastructure is required to capture the required data. This is then processed into the bills and invoices. By implementing packet counting at the edges of the network the network operators can accurately meter the network traffic and charge the consumers accordingly. Packet counting may be implemented as an integral function of the edge and core routers, or as part of dedicated packet counting servers connected to the network. The collection of such metering information may have a large overhead on the network in terms of bandwidth and resource. This overhead may make the counting of the packets more expensive than the actual value of the packets themselves. This kind of metering may work well in an enclosed Intranet where the network operator has access and ownership of all the core and access routers and is able to carry out the required metering. Where full Internet access is available the access networks may only be able to partially meter user traffic over the network. In this case suitable charging schemes based on gateway traffic to/from the Internet may be implemented. Metering may also be implemented via network protocols such as Diameter [7] or RADIUS [22], which carry the accounting information with the data communication. There are also proposals to implement the metering of the network traffic on the end systems [2]. These proposals are similar to how electricity and water are currently metered at the point of consumption. This approach has the advantage of low additional

4 infrastructure and overhead, but with the disadvantage of possible fraud, and the requirement for accurate policing of the implemented metering. With metering proposals there are also the overheads associated with the reconciliation of the different metering data from the various network operators and providers involved. This problem is analogous to that of cheque clearance in the banking world and the roaming charges in mobile telephone networks. Content Delivery Networks Application and service providers on the Internet are moving towards the Content Delivery Network (CDN) [6] paradigm, as shown in figure 1. Pages Services Applications ISP Content Network Access Network Gateway Application The Internet Figure 1 Content Delivery Network Service Provider This involves creating vast on-line localised caches of Internet content close to the access points in the networks where the content is consumed. The services that may be delivered by such a model include video on demand, electronic books, news, stock quotes and trading, plus services yet to be developed and deployed. The introduction of CDNs will have an effect on charging and billing of Internet services and provision. The overhead involved in collecting the metering information between and within the CDNs may prove problematic and inefficient. The provider of the CDN does have supervision power on the network for the metering of the traffic passing through it, and can therefore implement policy based charging models according to that traffic. Aggregated Services With the introduction of wireless technologies for Internet access the opportunity to form ad-hoc Intranets with Internet connections become possible. Such a scenario may be a high street café with a wireless hub or base station that allows customers to join the network when within range. The wireless network may then provide aggregated services. These may include Internet provision, dedicated web services, local directory services, on-line secure payments and transactions for goods purchased from the network connection provider. The use of such an aggregated service model is becoming popular. The low cost of the required infrastructure for wireless networks makes this a very cost-effective option for public access points to the Internet. The scope for charging for such services is wide-ranging and includes the policies that the operators of the aggregated services wish to implement. For example, Internet access may be monitored and charged for by duration, by connection or by admission to the network. Admission to the network may be free of charge, combined with low-cost or free services and applications for customers of the host access network. The use of the localised or hosted services may be charged using differential rates to those for remote hosted services accessed using a suitable gateway. This garden wall approach is becoming increasingly common with commercial service providers as it provides revenue security and also a captive market for their products and services. Mobile Telephone Networks With the convergence of mobile telephony and the Internet, charging and billing for mobile Internet services becomes important to the many mobile network providers. The telephony networks have the advantage over the Internet networks that they are obliged to generate usage statistics and metering to enable the charging and billing of the network s users. With the introduction of 2G (WAP [28], and GPRS [11, 12]) and 3G [26] (UMTS [27]) services the mobile networks are also deploying metering which can be used to generate the charging and billing information. The main limitation at the moment with the charging and billing for mobile Internet services is the granularity of the captured data. The standard Network Elements (NE) used for 2G and 3G service currently only support charging functions down to the IP address level, and not the URL level of the Internet services being accessed. Without packet sniffing the data being communicated over the network the options for charging are severely limited. One way around this limitation is to host the content from the Internet to the mobile Intranet and offer this to mobile users as part of their subscription service as outlined in figure 2. The subscription can be either a standard contract or prepaid pay-as-you-go. The locally hosted content adds value that the network that can then be offered to the subscribers. The content can also be branded by the network provider so that it appears to be directly aimed at the network s

5 subscribers. This delivery model is similar to the content delivery networks and the aggregated service models already discussed. Both allow the branding of content and services. Application Mobile ISP 'Intranet' Access Network Gateway Application The Internet Figure 2 Mobile Internet Network Application The mobile Internet network differs in that the access network is specific to the mobile subscribers and not an open environment. Authorisation and admission control is implemented as part of the standard mobile network infrastructure, using SIM [12] cards. The mobile telephony companies welcome the garden wall approach as it secures their business with the existing voice subscribers. When the network provider owns the locally provided content and the content servers, metering can be done with more granularity. This can be achieved by using the server logfiles and other mechanisms to record the metering information required for the local Intranet. This approach may be extended to include logfiles provided by trusted service providers on the Internet. Charging and billing using this approach may be thought of as charging by proxy, since the charging and metering is delegated to other service providers in the network. The consumer s ISP, or possibly another Internet Content Provider or Content Broker can then aggregate this data. Such arbitrage of services and content delivered via the Internet is an interesting development and one set to increase with time. The Impact of Mobility on Internet Charging Mobile users will generally pay high prices for the advantage of mobility but the trade-off of reduced Quality of Service. This willingness to pay will probably continue with the introduction of the 2G and 3G mobile Internet services. This should motivate the mobile network providers to introduce tariffs to take advantage of these new revenue streams. The introduction of the 'always on' connection based services such as GPRS and UMTS may have a large impact on location based services for mobile users. With current mobile telephone technology the location awareness is limited as are the applications that may be offered and supported. With time this functionality may improve. In parallel with this the improved awareness may begin to impose on the privacy of the users and these are concerns that need to be addressed. The mobile networks have already invested heavily in the licence costs for the 3G networks and more is required to provide the network infrastructure for these services. This infrastructure investment also includes the new billing systems associated with the mobile data services. Charging and billing for mobile services is an important issue for the mobile networks, and clear direction on how to charge for the spread of services on offer is required. Electronic Purse and wallets The mobile telephone is rapidly evolving into an electronic wallet to drive forward the cash-less society. Secure payment methods, such as SET [23] and ecash [8], allow mobile telephones with Internet connectivity, to become mobile purse and wallets. The same transactions may also take place from fixed Internet terminals but without the flexibility that comes with the mobility. Charge or credit card transactions are commonplace on the Internet today, with new trust based payment methods already being implemented and deployed. Security is a real concern with any Internet based transaction, and the world s press is littered with examples of Internet fraud. Sufficient precautions and safeguards need to be put in place to ensure that secure transactions may take place in a safe and trusted manner. From a security viewpoint the use of credit and debit cards for Internet transactions are considered a safer option as the card companies provides an added buffer and insurance against potential fraud for the consumer. 4. Current research Work Charging Platform Architecture To support the research into the charging and billing of Internet services an experimental charging platform architecture has been specified and designed as outlined in figure 3. This architecture facilitates the development and automated running and analysis of network charging and billing experiments. This architecture facilitates the development and automated running and analysis of network charging and billing experiments. The charging platform is hosted using Open Source software on standard PC hardware. The Linux operating system is used as the foundation of the platform. This provides a host of communication protocols as standard, as well as production standard applications, such as web servers,

6 programming languages and network support. These can be integrated to meet the requirements for this research. The availability of various communication protocols on the charging platform is important to ensure that the required charging data can be captured from the various charging points in the network under test. Results Server Control Queries Based Interface Edge Router PHP & Perl Scripts MySQL Database Apache Server Charging Platform Network Under Test (eg IP-Multicast) Core Router Core Router Core Router Edge Router Test Scripts Source Code Test Results Test Reports End System End System Figure 3 Charging Platform Architecture End System The charging platform includes an SQL database backend, together with a web server front end, which is used for visualisation and processing of the database contents. Scripting languages such as Perl and php are used as the main interface to the databases. These enable the rapid prototyping of experiment configuration and result presentation. The use of the web page interface as an abstraction layer between the charging platform and the end-user makes the platform more usable and accessible to researchers than a standard command line interface implementation. The charging platform is an ISP and operator centred approach to charging in the Internet. The design of the charging platform allows the architecture to scale for increased network size and also traffic capacity. This is achieved by the addition of further networked PCs running the same Open Source software. Distribution of the computational applications reduces the total throughput and capacity requirement on each distributed host system. This also reduces the additional network traffic necessary for the capture of the metering information from the network. As the number of users increase so does the number of charging platforms distributed in the network to support the charging function. These distributed charging platforms may be standalone systems or clustered together. The charging platform architecture resembles a mediation device as defined by the ITU [15] as currently used in many telephony networks. The mediation function can be performed by the charging platform or by external mediation devices, or a combination of both. Added value comes in terms of the services and applications that can be used on the charging platform for the complex manipulation and modelling of the captured data. This is in contrast to the simple filtered routing and translation that is performed by a standard telephony mediation device. 5. Research Objectives This research work is ongoing and a number of research objectives have been identified that the charging platform is currently supporting: Charging using AAA architectures This research includes the investigation and evaluation of the AAA architectures proposed by the IETF and IRTF [1, 13, 14]. An evaluation of Diameter is being made, in terms of meeting the accounting requirements for different network applications and environments. This will hopefully provide direct feedback to the work and research groups concerned with the Diameter protocol in the IETF and IRTF. Performance overhead evaluations for Diameter and the AAA architectures are also key research areas that the charging platform will address. Charging for Content Charging for content is still in its infancy on the Internet with only very basic mechanisms in place so far. With the introduction of services like Napster the implementation of charging and protection of content such as music, video and published material are a possibility. This has become an important and relevant area that is being researched with the support of the charging platform. Additional Charging Mechanisms The charging platform is being used to research alternative charging mechanisms for the Internet and Intranets, including packet charging approaches and web site statistics approaches. How network providers can implement their charging and billing infrastructure in a cost-effective manner is also being researched with the charging platform. Research into methods for the charging of emerging Internet standards such as MPEG- 4 (multimedia content) is also being carried out with support of the charging platform. As the research continues, further additional charging requirements may evolve that require support from the charging platform. Charging Models and their application The analysis of charging model implementation is an important objective of this research. A common figure attributed to the cost of providing customer bills in a

7 telecommunications network is approximately 40%+ of the annual revenue stream. An objective of this research is to propose methods to significantly reduce this figure. A further objective is to increase the revenue that the charging and billing can generate. The possibility to charge differentially for multiple levels of service, application and content provision is also a research objective. Internet and telephony companies have so far implemented limited charging models, based usually on subscription, capacity and duration charging. There are currently few other proposed models being advertised by the mobile network providers even though the new 2G and 3G services are almost imminent for consumers. The wireless network providers have similar charging limitations for their access point infrastructure. Deployment on real networks The use of realistic networks and traffic with end users and applications is an important objective of this research. This will make a valuable contribution to this research work. Past Research has show that when charging models are implemented without real cost to the users their network usage is not realistically affected. Only when real payment and cost is involved are realistic effects recognisable in the network. The charging platform is used to capture and process live data from wireless and fixed Internet networks as well as experimental laboratory based networks. Presentation of Results The data captured by the charging platform is stored to an on-line database that enables the use and study of various charging models with both live and simulated network traffic and data. Investigation and validation of the use of HTML, Perl and PHP to process and display back the raw data into presentable information is an important objective of this research. 6. Observations This research is ongoing but already observations on the use of the charging platform have been made. To make the implementation and study of various charging models possible, the charging platform has to capture sufficient data from the network. This data is required to describe and meter the resources that the service and applications are consuming and also to identify the parties to be charged. The amount of data that needs to be captured to enable this metering and charging to take place in a network is very large and one role of the charging platform is to reduce this to manageable levels. This has to be done without losing the data granularity required to be able to make good use of the information. The ability to combine and use different network metering and measurement on the charging platform allows for greater flexibility in the charging models that can be studied. 7. Related Research Work The main efforts currently being tracked by this research include the following: The IETF [13] and IRTF [14] working group and research group investigating authorisation, admission and accounting (AAA) [1] of Internet usage. The Market Managed Multiservice Internet (M3I) [18] project presenting research for charging and billing for Internet access in both fixed and mobile networks. The focus here is on next generation networks. The COST263 Action [21] (Quality of future Internet Services, QofIS) includes research into charging and billing of future Internet Services, and also associated Quality of Service issues and challenges. QoS-based charging and accounting for premium-ip services has been researched in the SUSIE [25] project, which resulted in valuable observations and results including live user trials. Commercial customer care and billing companies are starting to roll out content based charging systems. The implementation are not described openly, with most based on packet counting schemes when the user is charged for the amount of data consumed and not directly related to the content. Recent research work supports the case for flat rate charging for basic Internet services, but with the option for additional charges for premium services. Research at Columbia University [29] concludes that in a DiffServ environment, dynamic pricing based on level of service, usage and congestion enables more competitive pricing, a more efficient use of the network, and incentives for user adaptation. In the INDEX project at the University of California at Berkeley [30], a simple pricing scheme based on a combination of flat-rate and usage level is shown to provide benefits for both users and ISPs. Joint work between Microsoft Research and the Judge Institute in Cambridge, UK, [31] proposes a scheme to share network bandwidth and offer appropriate QoS by using congestion pricing as a means of providing feedback and incentives to end systems. 8. Further Research Work Evaluation of the IETF and IRTF AAA architectures [1] and how they may be implemented and deployed needs further investigation and research. This includes how they may be used effectively in the evolving Internet services and applications environment. A further stage of research involves extensions to the existing Internet

8 communication protocols. This involves investigating how charging and billing may be implemented using low-cost efficient methods and techniques. These will hopefully be attractive to providers and consumers alike. Research is also needed to address the Quality of Service (QoS) issues present in the Internet today, with focus on how QoS can be improved through charging and billing mechanisms. Evaluation of charging and billing schemes on simulated and/or realistic networks is also an essential research area for further investigation. This requires support from network operators, but since network performance and utilisation are often closely guarded secrets this may prove problematic, due mainly to commercial sensitivity. 9. Conclusions This paper has presented some of the different delivery models used on the Internet today for various services and applications. The technical requirements of the charging and billing infrastructure for Internet services and applications have been presented and discussed. The charging platform architecture (under development) has been presented together with an outline of the research objectives that the platform is supporting. This platform provides a valuable research tool hosting the development environment for charging and billing experiments, as well as an archival and presentation medium for the experimental results. The use of charging models for the Internet is evolving, and the move to combined models that borrow from each other is starting to be seen in the market. With the introduction of charging for content the combined model is welcomed as it allows the consumer to be charged for the transport as well as the goods. Charging only for the transport negates the value of the content, and deprives the service providers from valuable revenue streams. The technical challenges in capturing the required data and information are clearly understood. The direction network operators will take on charging for Internet services and applications is not clear. The need is for new approaches for capturing the charging information and the subsequent processing into bills and invoices. This calls for innovative as well as incremental research, which may then lead the way to original and lightweight methods that may be deployed in the Internet and private Intranets. Acknowledgement: Many thanks to HP Labs for the support of this work through an Industrial CASE Award in co-operation with the EPSRC. 10. References [1] AAA - RFC Criteria for Evaluating AAA Protocols for Network Access - [2] B. Briscoe, M. Rizzo, J. Tassel, K. Damianakis, Lightweight Policing and Charging for Packet Networks, Proc. Third IEEE Conference on Open Architectures and Network Programming (OpenArch 2000), pp.77-87, March 2000 [3] British Telecommunications [4] Charging and Accounting Technologies for the Internet (CATI) [5] D. Clark, A Model for Cost Allocation and Pricing in the Internet, MIT Workshop on Internet Economics, (ISBN ), March 1995 [6] Content Delivery Networks - Internet Draft [7] Diameter [8] ecash [9] ETSI NA8 GONOW [10] Freeserve [11] General Packet Radio Service (GPRS) [12] GSM Association [13] IETF AAA WG [14] IRTF AAA RG [15] International Telecommunication Union (ITU) TMN [16] B. Kahin, J. Keller (Eds), Public Access to the Internet, Cit Press, (ISBN: X), September 1995 [17] L.W. McKnight, J.P. Bailey (Eds), Internet Economics, MIT Press, (ISBN ), April 1997 [18] M3I [19] Micropayments [20] A. Odlyzko, The Internet and other networks: Utilization rates and their implications, Proc. 26th Telecommunications Policy Research Conference, October 1998 [21] QofIS 2000, 1st International workshop on Quality of future Internet Services [22] RADIUS - RFC Remote Authentication Dial In User Service [23] Secure Electronic Transaction [24] S. Shenker, D. Clark, D. Estrin, S. Herzog, Pricing in Computer Networks: Reshaping the Research Agenda, ACM Computer Communication Review (26) 1996, pp [25] SUSIE Charging for Premium IP Services [26] Third Generation Partnership Project (3GPP) [27] UMTS Forum [28] Wireless Application Protocol [29] X. Wang, H. Schulzrinne, Pricing Network Resources for Adaptive Applications in a Differentiated Services Network, Proc. IEEE INFOCOM 2001, Anchorage [30] J. Altmann, K. Chu, A Proposal for a Flexible Service Plan that Is Attrative to Users and Internet Service Providers, Proc. IEEE INFOCOM 2001, Anchorage [31] A. Ganesh, K. Laevens, R. Steinberg, Congestion Pricing and User Adaptation, Proc. IEEE INFOCOM 2001, Anchorage